Power supplies for producing high-frequency electric power from a direct current have widely been employed to supply electric power to laser oscillators. In order to generate high-frequency electric power, it is necessary to employ a laser oscillator control circuit for producing a pulse train to control the high-frequency electric power.
The laser oscillator control circuit has heretofore been constructed of a variable oscillator with its oscillation frequency variably dependent on the input voltage. The variable oscillator has been advantageous in that its output pulse train can freely be varied by varying the input voltage.
However, since the variable oscillator is operated under analog control, the accuracy of the pulse train is not necessarily sufficient under the influences of temperature, aging, and the like. When the off-time of the pulse train is zero (i.e., when the oscillator is 100% on) and when the on-time of the pulse train is zero (i.e., when the oscillator is 0% on , the laser oscillator control circuit of the conventional analog control type has to be controlled in special modes. Therefore, the control process is complex and the number of parts required for the control process is large.